1. Field of the Invention
The present invention relates to a device for preparing bone cement, and particularly to a container in which liquid monomer and powder polymer bone cement components may be mixed in a substantial vacuum.
In surgical applications in which natural joints are replaced by prosthetic devices, bone cement is commonly used to secure the prosthetic device to the bone of the patient. Bone cement is typically comprised of a powder polymer and a liquid monomer which polymerizes about the powder polymer. The preparation of bone cement comprises the step of mixing the liquid monomer with the powder polymer in a suitable container until a homogenous cement composition is formed.
Because the mixing of the liquid monomer with the powder polymer often generates obnoxious fumes and because preparing the bone cement in an open environment has been seen to result in the cured bone cement having a degree of porosity, devices have been created which allow the powder polymer and the liquid monomer to be mixed in a substantial vacuum. These devices are typically complex structures which result in increased medical costs because, in many instances, the devices must be thrown away after a single use. As a result, an inexpensive, disposable device is needed to prepare bone cement for surgical applications.
2. The Relevant Art
Devices exist for mixing bone cement for prosthetic applications. For instance, Smith U.S. Pat. No. 5,398,483 and Magnusson U.S. Pat. No. 5,370,221 disclose bone cement containers having dual, side-by-side compartments for separately maintaining the liquid monomer and powder polymer bone cement components, and a removable seal which separates the two compartments.
Tepic U.S. Pat. No. 5,051,482 discloses an apparatus for preparing bone cement, comprising a syringe and ampoule assembly for mixing the cement ingredients.
Wild U.S. Pat. No. 5,433,526 discloses a flexible, disposable bag for holding a liquid and/or pasty composition and having an opening for dispensing the stored composition.
Koyanagi U.S. Pat. No. 5,388,910 discloses a flexible bag having a valve which allows egress of air while preventing any ingress of air into the bag.
Herrington U.S. Pat. No. 4,532,652 discloses a flexible plastic bag having a one-way valve for discharging air therefrom.
Yasumura U.S. Pat. No. 4,917,684 discloses a flexible plastic bag having at least one coverable port.
The above-cited references, however, fail to disclose or otherwise suggest a disposable and inexpensive container for mixing bone cement ingredients.